Combined analysis with amniotic fluid index and estimated fetal weight for prediction of severe macrosomia at birth.

OBJECTIVE

To evaluate combined analysis with amniotic fluid index (AFI) and estimated fetal weight (EFW) for prediction of severe macrosomia at birth.

STUDY DESIGN

In this retrospective case-control study, 50 term severe macrosomic newborns (birthweight [BW] > or = 97th percentile) were included in the study group and 100 appropriate for gestational age newborns served as controls. All pregnancies underwent a third-trimester sonographic evaluation in which AFI and EFW were measured. The association between BW and AFI and EFW percentiles was examined. The statistical analysis included Student t test, simple regression and receiver-operating curve analyses, and 2x2 tables.

RESULTS

The mean mid-third-trimester AFI percentile and EFW percentile in severe macrosomic infants were 72.4 +/- 22.5 and 83 +/- 12, respectively, which was significantly higher than in controls (P < .0001). Significant correlations were detected between BW and AFI and EFW percentiles (r = 0.44 and r = 0.72, respectively; P < .0001). Receiver-operating characteristic analysis identified AFI > or = 60th percentile and EFW > or = 71st percentile as best predictors of severe macrosomia. The combined analysis with AFI > or = 60th percentile and EFW > or = 71st percentile resulted in a positive predictive value of 85%.

CONCLUSION

There is a significant correlation between mid-third-trimester AFI and BW. AFI > or = 60th percentile and EFW > or = 71st percentile during the mid third trimester are useful predictors of severe macrosomia at birth.